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Post by mrgrimsdale on Oct 4, 2008 7:27:55 GMT
I intend on putting DG in my house because my single glazed windows are like open fridge doors in the winter . The fact that my new windows have been sat in my garden for the last ten years is another matter  Sorry Jason we seem to have gone off at a tangent and hijacked your thread talking about environmental issues. What about having another section for trad woodwork - I'm not the only one fiddling about with old bits of junk and trying to copy them? Trad building and green issues also go together. cheers Jacob |
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Post by jfc on Oct 4, 2008 8:55:00 GMT
Good idea . I just need to work out how to move the posts  |
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Post by mrgrimsdale on Oct 4, 2008 9:01:13 GMT
Good idea . I just need to work out how to move the posts We can do it ourselves by copying and pasting. No Prob |
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Post by jake on Oct 4, 2008 12:04:45 GMT
Brian got there before me! If you factor in obsolescence its a different picture - DG units last 10/20 years, trad sashes last 100/200 years. It's a no brainer, you hardly need to do the sums. But the stats you were quoting must be based on full replacement, so are totally misleading in terms of payback time. That kind of catastrophic failure ^^ must be very rare. So you are really dealing with misting up problems - no reason in theory why the units can't be split and remade, with minimal enviro impact (whether that's ever done in practice is another question). I've got hideous late 70s/early 80s aluminium windows some previous idiot installed on our frontage - no problems with them at all (apart from their total hideosity) and they must be getting nearer to 30 years old. No doubt the whole uPvC/replacement for replacements sake is nonsense, but if the window is beyond repair (or it's a new opening), and the window frames/sashes need replacement anyway... |
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Post by modernist on Oct 4, 2008 13:41:48 GMT
Woah, wtf happened there? Good question! it only did that one the one morning. Must have been unusual weather but clearly the seal has gone. The problem is this is a 5m x 4m glass wall with the patio door in the middle. We are 1000ft up and completely exposed to the point that the trees lean over 20 deg and the building inspectorate forbade the use of cavity wall foam on the grounds that the horizontal rain will be "running down the inside of the cavities" and therefore needed air to breathe (Bet you like that Jacob!) Every cloud - it will give me the opportunity to put the drain holes in the bottom rail that I forgot in the rush to get the glass in put the grooved beads to the test  I'll let you know how I get on  Brian |
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Post by mrgrimsdale on Oct 4, 2008 15:14:51 GMT
snip Must have been unusual weather but clearly the seal has gone. snip Sad fact of life this but a lot of people with failed DG units put it down to special circumstances or bad luck. In fact it's extremely common. I don't really know what the failure rate in say 5 years would be, but wouldn't be surprised if it was 50% ish. One year not uncommon. Sometimes the whole batch - and the supplier has done a runner  cheers Jacob |
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Post by tusses on Oct 4, 2008 20:27:09 GMT
excuse me since when did 10 years old get to be new  is this jacob mathematics ;D paul  well my house is 200 yrs old so my misted up 10 yr old double gazing could be considered new ? ! and needs replacing. I am very tempted to go back to original !!! it would look a whole lot better for start ! |
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Telos
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Post by Telos on Oct 5, 2008 11:30:58 GMT
... it will give me the opportunity to put the drain holes in the bottom rail that I forgot in the rush to get the glass in put the grooved beads to the test... What exactly have you used to seal the glass in place? I can't make out any mastic or rubber seal in your first photo.... and if you haven't left any air circulation gap around the entire DG panel and/or drain holes at the bottom of the frame or bead, then that is the reason your glass has failed... |
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Post by modernist on Oct 5, 2008 18:51:06 GMT
There is an air gap all round and the pane is standing on glazing blocks. I sealed the outside only with low mod silicone and left the inner beads dry.
What do you think?
Brian
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Post by jfc on Oct 5, 2008 18:55:10 GMT
Whats the point of leaving an air gap around a sealed unit |
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Telos
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Post by Telos on Oct 6, 2008 9:15:50 GMT
There is an air gap all round and the pane is standing on glazing blocks. I sealed the outside only with low mod silicone and left the inner beads dry. What do you think? Brian Sounds perfect to me. You must have been very unlucky and received a duff unit. If the only thing you are missing are vent holes, the unit shouldn't have failed in less than a year. Still, it must be covered by the manufacturer guarantee? Or did you fit it yourself.... In which case begging and grovelling might be required. Just, re-read your post, the inner beads are sealed to the glass with dry rubber seals, yes? If you left them completely open to the air inside your house, then the moisture in the air will be condensing on the sides of your DG unit, which is "not a good thing". The frame must be sealed to the glass all round, inside and out, with external venting at the bottom. |
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Telos
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Post by Telos on Oct 6, 2008 9:20:40 GMT
Whats the point of leaving an air gap around a sealed unit It is essential for the longevity of the DG Unit. Contact with the frame must be avoided completely, which is why the plastic blocks are used. They also have a secondary, but vital function, of allowing air to circulate around the unit to equalize air pressure and vent any moisture that should sneak behind the seals to escape to the outside. Units that are not correctly installed may last 10 years if you're lucky, or 6 months if you're not. |
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Post by jfc on Oct 6, 2008 9:56:05 GMT
I understand the no contact with the frame but why not fill the gap with mastic , other than its a waste of mastic .
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Telos
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Post by Telos on Oct 6, 2008 10:51:25 GMT
I understand the no contact with the frame but why not fill the gap with mastic , other than its a waste of mastic . Read on young Padwan... ... They also have a secondary, but vital function, of allowing air to circulate around the unit to equalize air pressure and vent any moisture that should sneak behind the seals to escape to the outside.... No air gap (including equalized air pressure) = potential DG unit seal failure |
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Post by jfc on Oct 6, 2008 11:03:22 GMT
My point is if the gap is filled with mastic there will be no moisture . As for equalizing air pressure , its a window not a space ship ;D
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Telos
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Post by Telos on Oct 6, 2008 11:59:20 GMT
Yeah, I know it sounds ridiculous but the spacerbar seals are very sensitive (poor things). If a unit is exposed to a fluctuating pressure gradient (ie varying pressures which are not equal on both the internal and external faces of the unit) then the seal is repeatedly stressed, which can cause failures.
Completely filling the gap with mastic potentially causes two problems as not only can the unit not move freely depending on the pressure across the unit but water has an amazing ability of getting everywhere. Even good, intact mastic seals can let some water vapour through (as can painted wooden frames as well). If this cannot evaporate and vent into external air then it can accumulate on the DG seals which can also cause failures.
Amazing innit?
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Post by jfc on Oct 6, 2008 15:45:32 GMT
Hmmmm , lucky i'm tight with the mastic then . Main frame jointed .....  And a dry fit before glue up ....  |
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Post by jfc on Oct 6, 2008 16:57:01 GMT
Now i have the frame sizes i can start making the sashes . The sashes need to overlap at the center so i need to make each sash 32.5mm longer than the middle of the opening ( I am using 65mm stock for the sash rails .) I have also made the meeting rail on the top sash 10mm thicker than the rest . The traditional sashes have an angle on each meeting rail to take up the gap left by the parting bead but this makes fitting a lock on the sash very tight so by putting it all on the top sash it gives more room . Its suprising no one has picked up on this and started to supply thinner sash locks |
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Post by mrgrimsdale on Oct 7, 2008 6:21:27 GMT
Yeah, I know it sounds ridiculous but the spacerbar seals are very sensitive (poor things). If a unit is exposed to a fluctuating pressure gradient (ie varying pressures which are not equal on both the internal and external faces of the unit) then the seal is repeatedly stressed, which can cause failures. Completely filling the gap with mastic potentially causes two problems as not only can the unit not move freely depending on the pressure across the unit but water has an amazing ability of getting everywhere. Even good, intact mastic seals can let some water vapour through (as can painted wooden frames as well). If this cannot evaporate and vent into external air then it can accumulate on the DG seals which can also cause failures. Amazing innit? I don't have anything to do with DG but the air gap idea is interesting. It's also a basic principle of trad external joinery. Properly done, every door frame or window is fitted with an air gap between it and the masonry, including the cill. It's closed by the minimum possible amount of mastic at the outside, and usually by lime plaster on the inside - not allowing it to fill the gap. The bottom of a window frame will stand on a few bits of packing, slate, tile etc or have a designed masonry cill with a fall etc. Also the back of the joinery where it faces the masonry is never ever painted, so it can 'breathe' i.e. get wet occasionally but also be able to dry out. That's why it lasts so long esp sashes which have a well ventilated box construction. Where modern stuff is painted on the back, and packed tight with impervious mortar/mastic all round the gap - you get rot. In fact you can get water-logged cills, where once the paint outside or other detail has failed, the cill can literally fill up with water and rot away in no time. So it's good to know that modern window installers are slowly learning tricks which trad joiners have known all about for generations ;D cheers Jacob |
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Post by andy king on Oct 7, 2008 7:27:41 GMT
Closer to the fact would be that its to allow for the fact that not all bricklayers lay plumb and level.
Using a rod to take site measurements, the joiner will work to the smallest size, check diagonals etc, still allowing clearances to pack and fit the frames squarely within an opening that isn't always as good as it should be, unless the brickie has built to dummy frames.
It's common practice.
(I've also removed or replaced plenty of old joinery where its been painted on the backs during alterations, so not 100% gospel on both counts)
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Post by mrgrimsdale on Oct 7, 2008 7:43:34 GMT
snip (I've also removed or replaced plenty of old joinery where its been painted on the backs during alterations, Really? Why would they paint the backs? Waste of paint amongst other things. I think you are probably imagining it. Or it wasn't that old. cheers Jacob |
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Post by jfc on Oct 7, 2008 8:09:27 GMT
I think the waste of paint thing is more like it . When i worked for a preservation company the golden rule was to prime everything . It was quite interesting to go through a rotten building ( sometimes as big as churches ) and see where the rot had left the primed timber alone and totally destroyed unprimed timbers . I think with todays paints its worth priming everything .
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Post by mrgrimsdale on Oct 7, 2008 8:30:50 GMT
I think the waste of paint thing is more like it . When i worked for a preservation company the golden rule was to prime everything . It was quite interesting to go through a rotten building ( sometimes as big as churches ) and see where the rot had left the primed timber alone and totally destroyed unprimed timbers . I think with todays paints its worth priming everything . What for if it's out of sight? In the wrong place may keep water out but it can also keep it in. Thats my experience after removing 1000s of old windows and a few modern ones. cheers Jacob |
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Post by jfc on Oct 7, 2008 9:16:12 GMT
To prevent rot and insect attack . Like you i have seen a few windows and seen where priming has prevented rot attack .
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Post by mrgrimsdale on Oct 7, 2008 9:41:58 GMT
Well all I can say is, since I first noticed in about 1986 that old joinery (door & window frames pre 1900ish) is never painted on the backs, that I've never seen a single exception. Not one. I've seen a lot of stuff, Britain and Ireland, and I'm a bit obsessive about details . On the other hand the very worst water logged frames have been fairly modern and well painted behind and under, and crammed in with mastic, mortar etc. Or old frames of course when paint (outside faces) has been neglected for a very long time like 50 years or more. If I was a betting man and someone out there was about to remove a pre 1900ish frame, I'd put a big bet on there being no paint on the backs. Bound to be the odd exception due to odd circumstances, but I've never seen one. I can only say what I've seen! cheers Jacob |
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